UIs not working in new scene when previous scenes are loaded

I am loading multiple scenes into a new scene. One of the loaded scenes have two transparent large button that covers the whole canvas. The reason to do that is to give the user freedom to tap any part of the screen. However, I face problem in my new scene and the UIs (buttons and sliders) in the new scene are not clickable. I have tried loading the scenes in different order and also make the previous canvas disabled when loading the corresponding scene but it does not solve the problem and the UIs in the new scene are still not clickable. Any suggestion to address such problem?